The ruling on a traveler who prays the shortened prayer behind a resident imam

Your Eminence, this is a message from Rashid Abdullah from Dammam. He says: What is the ruling on one who prays the shortened prayer with an imam who prays the full prayer, meaning he prayed two rak'ahs with him and then said the closing salam, leaving the imam in his prayer?
Answer: In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, and blessings and peace be upon the Messenger of Allah, and upon his family and his Companions, and upon those who follow his guidance.
Answer: To proceed: Shortening the prayer is a confirmed sunnah (recommended practice) established from the Prophet (peace and blessings be upon him) regarding the traveler. However, if the traveler prays behind a resident, it is obligatory for him to pray the full prayer. This is the truth and the correct position held by a group of scholars. He does not have the right to shorten the prayer with the resident imam; rather, he must follow him and pray four rak'ahs with him. It is established from the Prophet (peace and blessings be upon him) in the hadith of Ibn Abbas (may Allah be pleased with them both) what indicates this. Ibn Abbas (may Allah be pleased with them both) was asked: , narrated by Imam Ahmad and Imam Muslim (may Allah have mercy on them both). This indicates that the sunnah is for the traveler to pray four rak'ahs with the imam, and if he prays with his traveling companions, he prays two rak'ahs. The one who prays with the resident imam while being a traveler and prays two rak'ahs with him is required to repeat the prayer. If he said the salam from that and did not follow his imam, he has erred and made a mistake. He must make up this prayer that he prayed with the imam and shortened; he must make it up by praying it as four rak'ahs, in accordance with this sunnah. Yes.